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Last Updated  9/20/2021

Influenza Season 2021-2022

During the 2019-2020 influenza (flu) season, the Centers for Disease Control and Prevention (CDC) estimated opens in a new tab that influenza was associated with 38 million illnesses, 18 million medical visits, 405,000 hospitalizations and 22,000 deaths. The season has been described as having moderate severity, with some variations noted by age group; for example, hospitalization rates among children 0-4 years old and adults 18-49 years old were higher than observed during the 2009 H1N1 pandemic.

Influenza activity (incidence, hospitalizations and deaths) was unusually low throughout the 2020-2021 flu season both in the United States and globally. One explanation is the COVID-19 mitigation measures put in place during the pandemic, such as wearing face masks, staying home, hand-washing, school closures, reduced travel, increased ventilation of indoor spaces and social distancing.

Preliminary national burden estimates for the 2020-2021 season are scheduled to resume later this winter. In the meantime, you can follow estimates (through Aug. 28, 2021), based on CDC’s weekly influenza surveillance data opens in a new tab.

Even healthy people can get the flu, and it can be serious.

The CDC recommends a yearly flu vaccine for everyone six months and older who do not have contraindications. Vaccination is important for those at high risk for serious complications, i.e., infants, children, adults >65, those with heart disease, asthma, diabetes and pregnant women. Healthcare staff are at risk for contracting the flu and transmitting it to their patients.

While seasonal flu viruses are detected year-round in the U.S., flu viruses are most common during the fall and winter. Flu activity begins in October and peaks between December and February, although activity can last as late as May.

The flu vaccine is the best way to protect against flu. Vaccination can reduce illness, doctors’ visits, missed work and school, and prevent hospitalizations.

Flu can cause mild to severe illness, and at times can lead to death. Flu is different from a cold. Flu usually comes on suddenly. People who have flu often experience some or all these symptoms:

  • Fever* or feeling feverish/chills
  • Cough
  • Sore throat
  • Runny or stuffy nose
  • Muscle or body aches
  • Headaches
  • Fatigue (tiredness)
  • Some people may have vomiting and diarrhea. This is more common in children than adults.

*It’s important to note that not everyone with flu will have a fever.

The CDC maintains information and resources on vaccination, infection control, prevention, treatment and diagnosis of seasonal flu opens in a new tab. Select resources were updated for the 2021-2022 season:
Advisory Committee on Immunization Practices (ACIP) –

Pregnant and postpartum women are at higher risk for severe illness and complications from the flu, particularly during the second and third trimesters. ACIP recommends opens in a new tab all women who are pregnant or who might be pregnant or postpartum during the flu season get a flu shot. For the 2021-2022 flu season, ACIP revised its guidance regarding the timing of flu vaccine for those who are pregnant and in the third trimester. Vaccination soon after vaccine becomes available is recommended because vaccination reduces risk for influenza illness in their infants during the first months of life (a period during which they are too young to receive influenza vaccine).

American College of Obstetricians and Gynecologists (ACOG) –

The ACOG opens in a new tab recommends pregnant women get a flu shot to protect both mom and baby.

Centers for Disease Control and Prevention (CDC) –

During flu season, CDC opens in a new tab considers pregnancy a high-risk situation and recommends pregnant women get a flu vaccine and in the form of a shot, not the nasal spray vaccine. Flu shots given during pregnancy help protect both mother and baby from flu. Evidence supports the benefits and safety of flu vaccine in pregnancy. Flu vaccine is also safe for breastfeeding women.

What are the differences among flu, COVID-19 and Respiratory Syncytial Virus (RSV opens in a new tab) infection?

  • While all are contagious respiratory illnesses, each is caused by different viruses. Flu is caused by infection with influenza viruses, COVID-19 is caused by infection with the coronavirus (SARS-CoV-2) and RSV by the respiratory syncytial virus.
  • Some of the symptoms of flu, COVID-19 and RSV are similar; it may be hard to tell the difference between them based on symptoms alone, and testing may be needed to help confirm a diagnosis.
  • There are vaccines available against both flu and COVID-19. At present, there is no vaccine against RSV.
  • There are some things we can all do to stop the spread of these infections:
    • Wear a mask.
    • Cover your cough/sneeze.
    • Wash your hands.
    • Mind your distance, especially indoors or in crowded locations.
    • Stay home if feeling unwell.

Image courtesy of Allan Foster via flickr licensed under CC BY-NC-ND 2.0.